[Effect of bioactive glass pretreatment on the durability of dentin bonding interface]

BG pretreatment of dentin bonding interface can induce mineralization at the bonding interface and reduce the microleakage of the hybrid layer; pretreating the dentin bonding interface with STMP, PAA and BG may enhance the maintaining of the dentin bonding durability. 目的: 研究生物活性玻璃(bioactive glass, BG)预处理对维持牙本质粘接界面耐久性的作用。 方法: 选取30颗无龋坏第三磨牙，去除冠部釉质制备牙本质平面，随机均分对照组、BG组、三偏磷酸钠(sodium trimetaphosphate, STMP)-聚丙烯酸(polyacrylic acid, PAA)-BG组(S-P-BG组)。各组均使用35%(质量分数)磷酸酸蚀牙本质样本，BG组再使用0.5 g/L BG涂擦酸蚀后的牙本质样本；S-P-BG组先使用5%(质量分数)STMP、5%(质量分数)PAA浸泡酸蚀后的牙本质样本1 min，再使用0.5 g/L BG涂擦牙本质样本。各组样本使用3M Single Bond 2粘接剂及3M Z350XT复合树脂粘接，并制备微拉伸柱状样本，每颗牙的柱状样本按时间随机分为24 h、1个月、3个月组。各组样本保存在37 ℃人工唾液(artificial saliva, AS)中相应时间后，进行微拉伸粘接强度测试，并使用单因素方差分析及LSD法进行统计学分析，扫描电镜下观察粘接断裂界面形貌。另选取27颗无龋坏第三磨牙制备牙本质平面，随机分为对照组、BG组、S-P-BG组，并按上述分组处理牙本质样本，再使用含0.1%(质量分数)罗丹明B的3M Single Bond 2粘接剂完成粘接。去除样本牙根暴露髓腔，并保存在37 ℃ AS中24 h、1个月、3个月后，髓腔内放置0.1(质量分数)荧光素钠溶液染色1 h，激光共聚焦显微镜观察粘接界面形态及混合层微渗漏。 结果: AS中浸泡24 h、1个月后，3组微拉伸粘接强度间的差异无统计学意义(P>0.05)；浸泡3个月后，S-P-BG组微拉伸粘接强度为(36.91±7.07) MPa，高于对照组粘接强度(32.73±8.06) MPa，且差异有统计学意义(P=0.026)；对照组、BG组3个月的微拉伸粘接强度较24 h呈下降趋势，且差异有统计学意义(对照组P=0.017，BG组P=0.01)；S-P-BG组3个月微拉伸粘接强度较24 h粘接强度[(37.99±7.98) MPa]下降, 但差异无统计学意义(P>0.05)。扫描电镜观察24 h粘接断裂面，3组均未见明显矿化；1个月、3个月后，BG组、S-P-BG组的粘接界面可见矿物质形成，S-P-BG组无明显胶原暴露。激光共聚焦显微镜观察对照组、BG组与S-P-BG组树脂突形成的形态及数量无明显差异；3组样本粘接24 h后粘接界面混合层均有渗漏，3个月后对照组微渗漏增加，BG组和S-P-BG组混合层微渗漏减少。 结论: BG预处理牙本质粘接界面能够在粘接界面形成矿物质，减少粘接混合层微渗漏；STMP、PAA与BG共同预处理牙本质粘接界面，可能在一定程度上维持牙本质粘接修复的耐久性。

In the study, 30 dentin planes were prepared from the third molars with no caries and equally assigned to the control group, BG group, and sodium trimetaphosphate (STMP)-polyacrylic acid (PAA)-BG group (S-P-BG group), randomly. After etched with 35% phosphoric acid, the dentin planes of BG group were pretreated with 0.5 g/L BG, and the dentin planes of S-P-BG group were pretreated with 5% STMP, 5% PAA and 0.5 g/L BG. No additional pretreatment was done to the dentin planes of control group. Then the dentin planes were bonded using 3M Single Bond 2 adhesive to 3M Z350XT composite resin, and cut into 0.9 mm×0.9 mm column samples, which were stored at 37 ℃ artificial saliva (AS). After 24 hours, 1 month, and 3 months, the microtensile bond strength test was performed. The data were analyzed using one-way ANOVA and LSD method. The morphology of the bond fracture interface was observed with scanning electron microscope. Other 27 teeth were collected and the enamel layer and roots cut off, with the pulp chamber exposed. 0.1% rhodamine B was added to the 3M Single Bond 2 adhesive, and then the adhesive was applied to complete the bonding procedures as above. The teeth were stored in 37 ℃ AS for 24 hours, 1 month, 3 months, and then 0.1% sodium fluorescein solution was placed in the chambers and stained for 1 hour. Confocal laser scanning microscopy was used to observe the interface morphology and microleakage of the hybrid layer.

To study the effect of bioactive glass (BG) on the dentin bond strength and the microleakage of hybrid layer.

At the end of 24 hours and 1 month, there was no significant difference in the microtensile bond strength among the three groups (P>0.05). After 3 months of soaking, the S-P-BG group [(36.91±7.07) MPa] had significantly higher microtensile bond strength than the control group [(32.73±8.06) MPa] (P=0.026); For the control group and the BG group, the microtensile bond strength significantly decreased at the end of 3 months compared with 24 hours (control group: P=0.017, BG group: P=0.01); The microtensile bond strength of S-P-BG group af the end of 3 months had no significant difference in compared with 24 hours [(37.99±7.98) MPa] (P>0.05). Observation of the fracture surface at the 24 hours showed no obvious mineralization in all the three groups. After 1 and 3 months, mineral formation was observed in BG group and S-P-BG group, and no obvious collagen exposure was observed in S-P-BG group. Confocal laser scanning microscopy revealed no obvious differences in the morphology and quantity of the resin tag in the control group, BG group and S-P-BG group. At the end of 24 hours, leakage was found in all the three groups. The microleakage of the control group increased at the end of 3 months, while the microleakage of the BG and S-P-BG groups decreased.